Mia, the irreverent, hyperanalytical twenty-year-old daughter, has an explanation for everything—which is why she isn’t initially concerned when her father and younger brother Eugene don’t return from a walk in a nearby park. They must have lost their phone. Or stopped for an errand somewhere. But by the time Mia’s brother runs through the front door bloody and alone, it becomes clear that the father in this tight-knit family is missing and the only witness is Eugene, who has the rare genetic condition Angelman syndrome and cannot speak.